This invention relates to a magnetic navigation system for applying a navigating magnetic field to an operating region inside a subject while simultaneously imaging the operating region.
Magnetic navigation systems have been developed which apply a navigating magnetic field in a selected direction to an operating region in a subject to change the direction of a magnetically responsive medical device in the operating region. Examples of such systems are disclosed in U.S. Pat. No. 6,241,671, issued Jun. 5, 2001, for Open Field System for Magnetic Surgery; and U.S. Pat. No. 6,630,879, issued Oct. 7, 2003, An Efficient Magnet System for Magnetically-Assisted Surgery, the disclosures of which are incorporated herein by reference. However for many procedures it is desirable to provide simultaneous or near simultaneous images of the operating region either to confirm the position and orientation of the medical device, or to otherwise control the medical procedure being conducted with the medical device. Imaging can be conveniently provided with a C-arm mounted x-ray imaging system, employing an imaging beam source and detector disposed on opposite sides of the operating region. However, the magnet systems employed in magnetic navigation systems typically must be positioned in close proximity to the subject in order to provide magnetic field of sufficient strength to be useful in navigation. Thus the magnet systems create an exclusion zone around the subject into which the imaging system cannot impinge, and this exclusion zone restricts the orientations at which the C-arm can be positioned for imaging.